1. Field of the Invention
The present disclosure generally relates to mandrels. More particularly, the present disclosure relates to mandrels that provide hydraulic sealing during injection molding.
2. Description of the Related Art
Components, such as jet turbine components, are often formed using molding processes. For example, a material in liquid form may be pumped or injected into a tooling whose inner surfaces will define the outer periphery of the component. The material solidifies within the tooling and then may be removed as a solid component. In some embodiments in which the component is to be formed as a composite component, fiber material, such as sheets of fiberglass, is laid within the tooling and liquid resin is then injected into the tooling and cured to form a solid composite component.
In co-molding processes, pre-formed parts are further provided within the tooling before material is injected into the tooling. In such cases, the pre-formed parts can be integrated into the component that is being formed. When a pre-formed part includes a cavity that is not to be filled with the injected material during the molding process, a mandrel may be used to occupy the cavity to prevent the material from flowing into the cavity.
Currently, there are various different types of mandrels that are used in molding processes, including cast ceramic mandrels, salt mandrels, low-melt alloy mandrels, trapped rubber mandrels, and machined metal mandrels. None of those mandrels, however, provide all of the properties that may be desired in a mandrel, particularly when a cavity is to be is isolated. Such properties can include, for example, sufficient rigidity during mandrel insertion, sufficient mechanical support and hydraulic sealing during the molding process, low mechanical stress during mandrel removal, and the absence of mandrel residue after mandrel removal.